How can we improve Premiere Pro?

Why can I shift (drag) select but not shift (drag) deselect

Selecting clips is great using shift and dragging to select large sections of a timeline but there is no ability to deselect in the same way.

Obviously you can shift click to deselect but if large amounts of clips need doing the frustration of mis-clicking and finding a cut in between two clips and cancelling the selection all together is rather annoying.

It would be great to have the ability to deselect clips similarly to shift-drag, maybe shift-cmd/ctrl-drag would work.

This feature already exists (and has done for as long as I can remember). You're just doing it slightly wrong.

When you want to deselect multiple clips, hold shift and drag across the selected clips - this is what you're already doing but there's a crucial next step. Before releasing the mouse button, drag your curser away from the currently selected clips to an empty part of your timeline. This will deselect them.